The present invention primarily is for use with a high volume evacuator, especially of the type employed in dental offices to withdraw from the oral cavity of patients flushing and cooling water, mouth fluids, and debris resulting from various dental operations, such as metal chips, tooth fragments and grindings, and the like. This type of fluid is known as "gray water" to signify that it is impure and not to be confused with fresh water, such as that obtained from a municipal supply provided in a dental operatory. Other uses are set forth below.
One widely used type of high volume evacuator is shown at least in basic principles in prior U.S. Pat. Nos. 3,482,313, to G. H. Stram, dated Dec. 9, 1969 and 4,245,989 to Richard P. Folkenroth et al, dated Jan. 20, 1981.
Essentially, the high volume evacuating system illustrated in the aforementioned patents includes a liquid seal pump which, at all times, must have a residue of liquid therein to operate it, such as by maintaining the pump primed, and while, at least initially, the priming water is clear fresh water, after the system has been operating for a certain period, the sealing water may constitute gray water which is of an unpure nature as far as human consumption is concerned. Nevertheless, the system is connected with a municipal supply of fresh water, and particularly, where systems of this type are located in high-rise buildings, it sometimes happens that the pressure on the municipal supply water to an operatory may dissapear due to certain failures, such as the municipal water pump for the building to be deactivated or otherwise malfunction, under which circumstances, it is possible for a vacuum to exist in the fresh water supply, and thus it is conceivable and actually possible for such suction to draw gray water from the pump or other residues of gray water in the high volume evacuator system and thereby contaminate the municipal water supply to the operatory.
To prevent such phenomenon from occurring, certain municipalities have required vacuum breakers or other suitable devices to be employed in lines associated with fresh water or municipal supply and, in an effort to comply with such requirements, the present invention has been developed to provide a relatively inexpensive means for preventing suction accidentally being imposed upon the fresh water supply, under the circumstances described above, as well as other situations described below.
Vacuum breaker structure per se are quite old. Typical examples of them are represented by the following U.S. Pat. Nos.: 2,655,171, Cantor, Oct. 13, 1953; 3,180,352, Kersten et al, Apr. 27, 1965; 3,713,457, McInnis et al, Jan. 30, 1973.
The present invention also includes float-operated valves, similar to those used in the water tank associated with toilet commodes and also for purposes of preventing siphoning of water from the tank into the fresh water supply connected to the tank. Essentially, structures of this type per se also are old and typical examples of these are illustrated in prior U.S. Pat. Nos. 2,111,614 to Cox, dated Mar. 22, 1938 and 2,941,542 to Jacobson, dated June 21, 1960.
While the present invention employs certain characteristics of the structure shown in the aforementioned prior patents, it, nevertheless, is directed to an overall different system than shown in the prior structures, details of which are set forth hereinafter.